Pyrazole derivatives

A process for preparing a compound of the formula:

• ##STR12## wherein R.sup.1 is optionally substituted aryl, or optionally substituted saturated or unsaturated, monocyclic or polycyclic heterocyclic group containing at least one hetero-atom selected from the group consisting of oxygen, sulfur, and nitrogen atoms,
• R.sup.2 is optionally substituted aryl, or optionally substituted saturated or unsaturated, monocyclic or polycyclic heterocyclic group containing at least one hetero-atom selected from the group consisting of oxygen, sulfur, and nitrogen atoms,
• R.sup.3 is hydrogen or acyl,
• R.sup.4 is hydrogen, lower alkyl, cyclo(lower)alkyl, cyclo(lower)alkyl-(lower)alkyl, carboxy(lower)alkyl, protected carboxy(lower)alkyl, ar(lower)alkyl which may have suitable substituent(s), ar(lower)alkenyl, bridged tricyclicalkyl, optionally substituted saturated or unsaturated, monocyclic or polycyclic heterocyclic group containing at least one hetero-atom selected from the group consisting of oxygen, sulfur, and nitrogen atoms, optionally substituted dioxaspiroundecanyl, acyl, or a group of the formula:
• ##STR13## (in which A is lower alkylene), and R.sup.5 is hydrogen or lower alkyl, or a salt thereof, which process comprises subjecting a compound of the formula:
• ##STR14## wherein R.sup.1, R.sup.2 and R.sup.5 are each as defined above, or a salt thereof to reduction reaction to give a compound of the formula;
• ##STR15## wherein R.sup.1, R.sup.2 and R.sup.5 are each as defined above, or a salt thereof or
• (2) subjecting a compound of the formula:
• ##STR16## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.5 are each as defined above, or a salt thereof to acylation reaction to give a compound of the formula:
• ##STR17## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.5 are each as defined above, and R.sub.a.sup.4 is acyl or a salt thereof.